[James Romeyn]

For liability issues let's all just presume this is a purely academic, hypothetical discussion.   

Elevation is 4900'.  As you might expect there's little if any problem when the furnace is not employed.  With the furnace employed painful & easily visible blue/white sparks result when touching the wall lightswitch &/or lamp, components or the metal equipment rack.  No diminution experimenting w/ different sole materials on footwear.  Apparently there would be some relief if a humidifier was added to the HVAC & that will probably happen sooner or later.  Someone said the voltages involed are huge (though currents are low to moderate).   

What about a capacitor bank, one end attached to the metal equipment rack?  The listener touches the open end of the capacitor bank to slow the discharge & store it in the capacitor rather than the normal immediate discharge.  Will that work?

Or a resistor wired & used in the same fashion as above?  One end attached to the rack, the listener touches the open end to partially discharge, then the remainder is discharged by directly touching the rack.  Will that minimize discomfort? 

Or combining a resistor & capacitor in series &/or parallel?  Is a humidifier the only answer?  Any commercial product?  Component values/ratings?  Polarized/non-polarized caps?

Would appreciate any ideas for this PURELY academic discussion.

Regards,
JR

[markC]

Don't even think about defying the physics of the fact that warm air can hold more moisture and cold air cannot. The colder it is outside, the more your furnace runs, drying the air inside your home. The colder it is outside, the less moisture the air coming into your home from outside contains. A dry-dry situation. Add a decent flow through humidifier and forget about fighting Mother Nature with capacitors!

[Speedskater]

Look up "Static Control Products"
Digikey is a good place to start:
www.digikey.com
Some other lab equipment or computer sites may have even more useful stuff.

[Bob in St. Louis]

What about a wire running to the houses plumbing?
The wire could be connected to the "touch point" on the equipment rack. The user would touch the special contact point before touching the equipment.

About once a month I blast one of my components with tens of thousands of volts from static electricity. 
My equipment rack has a wood framed glass door on it. I've contemplated using the stainless steel door pull on the glass and running a ground wire to it, so the shock hits the door harmlessly going to ground before it hits the expensive stuff.
It's on my 'to do' list. 

Bob

[2wo]

3M makes something called a "first touch strip" or something like that. It's a conductive pad connected to ground Through a very high Resistance.

Try a large value resistor, or even try rubbing a band of graphite from a pencil onto a strip of paper. tape one end to your rack so the track touches the metal  just to test the idea...John

[James Romeyn]

3M makes something called a "first touch strip" or something like that. It's a conductive pad connected to ground Through a very high Resistance.

Try a large value resistor, or even try rubbing a band of graphite from a pencil onto a strip of paper. tape one end to your rack so the track touches the metal  just to test the idea...John

John
Thanks for your ideas.  What's the high-low range for resistor values?  I searched Digikey.com & two pages at Dogpile.com & found nothing for the above-named "3M First Touch Strip".  Could it have a different name? 

I could just see the spark running across the graphite strip causing the paper to reach ignition temperature!  Wow!  Talk about a high-voltage sound system! 

Could we not minimize our dependance on foreign oil imports by harnessing this wasted power?  Teach our children to walk in a special way, dragging their feet as much as possible w/ graphite soles on orange shag carpets ala the '70s, then discharging into some type of power distribution system?          

[randytsuch]

At work, for ESD protection, we use something like this

http://www.electrowisehsv.com/content/products_subdirectory_details.php?cat3=Adjustable%20Wrist%20Strap%20with%2010'%20coiled%20cord,%20Burgundy

BTW, I have no idea about this company, just found them with a web search, but I am sure there are many others that sell wrist straps for ESD protection.  Any company that deals with electronics uses them.

We have ESD benches, so one end of the cord is plugged into the bench, and the other end is attached to the wrist strap.

At home, to do things like install an new PC motherboard, I put on a wrist strap, and plug it into the ground of an outlet. 
In your case, I would think if the wrist strap was hooked up to the metal rack, that it would dissipate the static, but you would have to try and see.

BTW, the strap might just be a wire with a 1 megohm resistor, so a cheaper way may method might be a 1 meg resistor to ground.

And, I don't think your cap method will help.

Randy

[Speedskater]

I saw some 3M Static Control Pads in an old Mouser catalog.
This material is just barely conductive. It's in the meg-ohm range, but that's all it takes to dis-charge you.

[James Romeyn]

I saw some 3M Static Control Pads in an old Mouser catalog.
This material is just barely conductive. It's in the meg-ohm range, but that's all it takes to dis-charge you.

You don't seem to understand...I'm trying to AVOID being dis-charged...to the emergency room that is!

[Bob in St. Louis]

Jim, Do you have a heart monitor/defibrillator installed?

Bob

[Speedskater]

With the 3M Static Control material, you don't get a spark. It's extremely high resistance drains the charge slowly. The silver bags that computer boards are packed in and that black foam that IC's are stored in work the same way.
Years ago when I was Chief Engineer at the radio station, we would spray an anti-static solution on the carpets with a garden sprayer.

[ctviggen]

What about a wire running to the houses plumbing?
The wire could be connected to the "touch point" on the equipment rack. The user would touch the special contact point before touching the equipment.
[cut]

Bob

It's better to attach the wire to a grounding point (such as provided on some equipment) or to the ground on an outlet.  This is because some houses use the plumbing as a ground, but many do not (including my house).  You'd therefore be connecting the plumbing to an ungrounded system (or if it is grounded, you'd be creating a ground loop with the true earth ground). 

By the way, most music equipment shouldn't be affected by a jolt of carpet-created static electricity.  For instance, analog amps probably won't be hurt.  Anything with CMOS (complementary metal oxide semiconductor) parts could be affected, though, such as HT preamps.  You might, however, make a popping noise that could be problematic.

[Bob in St. Louis]

Good information Bob, thank you.
Hopefully Jim can make use of what's been written here, I know I will.
But I still wonder if he's trying to save the equipment or himself?
I have a quick ON topic story that may be of some use....

A few years ago I worked at a Chevy dealership. We had a customer with an unusual complaint about his Chevy Trailblazer. In the wintertime as he exited the car, the last thing he would touch was the door frame of the car in order to close it. He claimed that on a regular basis, the static build-up created by sliding off the seat built up enough voltage that the resulting shock could possibly damage his pacemaker. Actually, he was fairly melodramatic when he exclaimed that he was "was afraid for his life". He claimed the car didn't do this when it was new, and that it was due to the fact we had the vehicles interior upholstery treated with "Scotchguard" when he purchased it new. A few years later the product had all but worn off the drivers seat because he slid across the seat when exiting instead of lifting his butt off of it. What he wanted was for us to recoat the interior (for free of course  ) with another treatment of Scotchguard (he told me he'd given his wife instructions on how to sue my dealership and General Motors if we didn't 'take care of him' and he died 'because of us'.
I obliged and re-coated the upholstery. He came back a few weeks later and profusely thanked me for potentially saving his life. I left the dealership a couple years later and he claimed he'd not gotten zapped since the last application.
I don't know if there's any truth to this 'Scothguard/static' thing or not, or if the guy simply wanted something for free. But for $10 worth of material, I figured "why not, make the guy happy".

Bob

[jneutron]

I don't know if there's any truth to this 'Scothguard/static' thing or not, or if the guy simply wanted something for free. But for $10 worth of material, I figured "why not, make the guy happy".
Bob

Happy customers are good customers.

There is indeed the possibility of truth.

We are talking about triboelectric charge generation, exactly like a van de graff.    Tribo works by the separation of two materials that have a difference in position on the triboelectric series.  By scotchguarding, one surface composition was changed.  I would guess just a shift along the triboelectric series, rather than a change in the surface conductivity.

Here's a look-see.

http://en.wikipedia.org/wiki/Triboelectric_effect

Humidity tends to allow charge buildup to leak away.

Cheers, John

[James Romeyn]

I'd say my priorities in sequence are:

1. Eliminate uncomfortable zapping.

2. Eliminate potential component problems.  One component often mutes on one channel or the other after being zapped (sometimes both channels after big sparks).  The mute often corrects by adjusting the volume control or activating the mute circuit.  The problem has escalated so that both channels sometimes mute w/o cause.  When both channels mute a re-boot is required, which unfortunately takes about 90 seconds, bummer. 

Rather than thinking the zaps broke the relay I'm thinking the relay was broken or borderline when new, because originally the mute repeatedly occured in only one particular channel.  The component will be shipped for a new relay after a low-priced replacement piece arrives (will probably be disappointed by the audio performance, but at least a movie can be veiwed while riding the wind trainer).   

[Speedskater]

Good information Bob, thank you.
Hopefully Jim can make use of what's been written here, I know I will.
But I still wonder if he's trying to save the equipment or himself?
I have a quick ON topic story that may be of some use....

A few years ago I worked at a Chevy dealership. We had a customer with an unusual complaint about his Chevy Trailblazer. In the wintertime as he exited the car, the last thing he would touch was the door frame of the car in order to close it. He claimed that on a regular basis, the static build-up created by sliding off the seat built up enough voltage that the resulting shock could possibly damage his pacemaker. Actually, he was fairly melodramatic when he exclaimed that he was "was afraid for his life". He claimed the car didn't do this when it was new, and that it was due to the fact we had the vehicles interior upholstery treated with "Scotchguard" when he purchased it new. A few years later the product had all but worn off the drivers seat because he slid across the seat when exiting instead of lifting his butt off of it. What he wanted was for us to recoat the interior (for free of course  ) with another treatment of Scotchguard (he told me he'd given his wife instructions on how to sue my dealership and General Motors if we didn't 'take care of him' and he died 'because of us'.
I obliged and re-coated the upholstery. He came back a few weeks later and profusely thanked me for potentially saving his life. I left the dealership a couple years later and he claimed he'd not gotten zapped since the last application.
I don't know if there's any truth to this 'Scothguard/static' thing or not, or if the guy simply wanted something for free. But for $10 worth of material, I figured "why not, make the guy happy".

Bob

In the mid 1990's some tire brands switched from carbon black to a new material that resulted in the tires having a much higher electrical resistance to the road. Lots of toll-booth operators got zapped!!

[James Romeyn]

Off topic but hey it's my thread!

Apparently at least one fatal fire has occured at a gas station.  It's winter, cold & dry.  Driver's heater was employed further drying the environment (often on newer vehicles the A/C is automatically employed in defrost mode to maximize efficiency; it also maximizes static charging).  Driver may also slide off the seat, further increasing their static charge. 

Driver removes plastic non-conductive fuel cap.  Driver next contacts only the fuel pump valve (not the pump body) then inserts the valve into the metal vehicle fuel neck.  The static electrical charge jumps from driver, through the pump valve through the metal neck to earth (or maybe battery negative?).  When the spark jumps from the valve to the neck the fuel tank fumes ignite. 

Solution: driver's first action, every time exiting the vehicle at a fuel station, must be to contact the fuel pump body to discharge at that point.

Static charge easily develops in metal fuel cans, especially when the can slides across a metal pickup truck bed.  That's why the can must go to earth to be discharged before inserting the pump valve. 

Fireman I worked with almost died jump starting a car.  The last connection made was the negative cable being connected to the dead battery (an ancient dillapidated unsealed battery with a high volume of concentrated fumes hovering just above it). 

Kaboom. 

Thus the safe sequence is:

Both vehicle ignitions off.
Hold one end red cable in each hand.
First end red cable to dead vehicle battery + terminal.
Second end red cable to good vehicle battery + terminal.
Hold one end black cable in each hand.
First end black cable to good vehicle battery - terminal.
Second end black cable to metal chassis/ground/earth point of dead vehicle at least 3-4' from battery (NOT battery - terminal because of proximity to potential fumes; circuit closes & spark may occur).
Insure connections are secure & cables are clear of fans etc. 
Start good vehicle, rev to 1/3rd max RPM, neutral, e-brake fully engaged, brake pedal depressed, all lights/accessories off.
Start dead vehicle. 
Cable disconnect is inverse of above.

[Bob in St. Louis]

The keys should be turned off and removed from the ignition when installing the jumper cables (of modern cars).
With the key on (or even IN the ignition) three dozen solid state control modules are powered up and unprotected from the voltage spike created by jump starting.
Where I work, the common smoked component is the cars audio amplifier. A $1,300 punishment for the vehicles owner that (obviously) already having a bad day. It's best to call roadside assistance and let them be responsible. If you're lucky, the guy that comes to help might be slightly more knowledgable about cars than you, but if nothing else THEY'LL be responsible for any damage not you. 
We replace about 2 amps per month due to improper jump starting techniques. cha ching 

Bob

[TomS]

Thanks for that great tip Bob.  It's soooo.. obvious, but in a panic I don't even think about all those modules that even the key insertion wakes up.  I'll remind my teen daughters too  (they usually call AAA).  Tom

[Bob in St. Louis]

Glad I could help Tom. Unfortunately, a good 50% of the fried amps we replaced were damaged by AAA or various other roadside assistance companies, or general tow truck drivers. I can only assume these guys are 'old school' enough that they're thinking of cars made 'back in the old days'. These guys need to be educated with modern automotive systems and their weaknesses.

Bob